In U.S. Pat. No. 3,509,840 and pending applications Ser. No. 833,178, filed Sept. 14, 1977, now U.S. Pat. No. 4,117,789, and Ser. No. 896,884, filed Apr. 17, 1978, there are shown and described bobbin spools for automatic sewing machines wherein a predetermined length of thread is wound onto a spool for each sewing operation. In U.S. Pat. No. 3,509,840, there are a plurality of small diameter wires extending parallel to the axis of the spool and spaced outwardly of the axis for catching the leading end of the thread. In U.S. Pat. No. 4,117,789, the leading end of the thread is entangled and caught by a layer of "fuzzy" material applied to the hub of the spool, for example, a stiff piled fabric or a piece of Velcro. The aforesaid means for entraining the leading end of a thread are quite appropriate for soft thread; however, when stiff, hard and/or slippery threads are used, there is a tendency for the leading end of the thread to slip and fail to be caught for winding onto the spool. It is, accordingly, the purpose of this invention to provide the spool with improved traction-engendering means especially designed to insure catching the leading end of stiff, hard and/or slippery thread.